The perils of shopping for holiday gifts online or sending packages too close to an impending birthday or holiday are well known. It’s all too easy to click ‘place order’ a day late and leave your Christmas stockings un-stocked because your order didn’t arrive on time.

Amazon, the world’s biggest online retailer, has a huge budget devoted to processing its holiday orders quickly this year. The company recently installed some 15,000 high-tech Kiva robots in its fulfillment centers to whisk items quickly into delivery, and last year, Amazon inked a deal with the U.S. Postal Service to offer Sunday shipping through the season.

As far as shipping other gifts to your relatives, the rules are a little more complicated because of all the parcel delivery services in the U.S. But no fear—TIME has compiled a list of handy deadlines for shipping gift packages via UPS, USPS and FedEx to friends and family in time for Christmas Eve arrival. A quick caveat: Unexpected weather and human error can always cause unexpected delays with any shipping service, so the earlier your order your gifts, the safer you’ll be.

FedEx

The last day to ship with FedEx via the standard ground shipping for pre-Christmas delivery is Wednesday, December 17.

For FedEx Express, the last day is Tuesday, December 23.

USPS

Do all your standard package shipping with the government-run postal service by Monday, December 15.

For sending greeting cards and priority mail, the last day is Saturday, December 20.

And for procrastinators out there, Priority Mail Express can be used until December 23.